/*
 * Copyright (c) 2004-2022, University of Oslo
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors 
 * may be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.hisp.dhis.system.velocity;

import java.io.StringWriter;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader;
import org.springframework.stereotype.Component;

@Component("org.hisp.dhis.system.velocity.VelocityManager")
public class VelocityManager {
  public static final String CONTEXT_KEY = "object";

  private static final String RESOURCE_LOADER_NAME = "class";

  private static final String VM_SUFFIX = ".vm";

  private VelocityEngine velocity;

  public VelocityManager() {
    velocity = new VelocityEngine();
    velocity.setProperty(RuntimeConstants.RESOURCE_LOADER, RESOURCE_LOADER_NAME);
    velocity.setProperty(
        RESOURCE_LOADER_NAME + ".resource.loader.class", ClasspathResourceLoader.class.getName());
    velocity.setProperty("runtime.log.logsystem.log4j.logger", "console");
    velocity.setProperty("runtime.log", "");

    velocity.init();
  }

  public VelocityEngine getEngine() {
    return velocity;
  }

  public String render(String template) {
    return render(null, template);
  }

  public String render(Object object, String template) {
    try {
      StringWriter writer = new StringWriter();

      VelocityContext context = new VelocityContext();

      if (object != null) {
        context.put(CONTEXT_KEY, object);
      }

      velocity.getTemplate(template + VM_SUFFIX).merge(context, writer);

      return writer.toString();

      // TODO include encoder in context
    } catch (Exception ex) {
      throw new RuntimeException("Failed to merge velocity template", ex);
    }
  }
}
